Method and apparatus for encoding and decoding a high speed shared control channel

ABSTRACT

A method and apparatus for encoding and decoding a data block are disclosed. The data block may be for a physical channel. Further, the data block may be for a shared channel. For data block encoding, a Node-B may calculate cyclic redundancy check (CRC) bits for the data block. The data block may be used to calculate the CRC bits. The Node-B may mask the CRC bits with a wireless transmit/receive unit (WTRU) identity (ID). Further, the Node-B may attached the masked CRC bits to the data block. Using a transmitter, the Node-B may transmit the data block over a physical channel. Further, the Node-B may transmit the data block over a shared channel. A WTRU may receive the data block, including the masked CRC bits. Using the WTRU ID, the WTRU may de-mask the CRC bits. The WTRU may perform a CRC check using the de-masked CRC bits.

CROSS REFERENCE TO RELATED APPLICATION

This application is a continuation of U.S. patent application Ser. No.14/083,054 filed Nov. 18, 2013, which is a continuation of U.S. patentapplication Ser. No. 13/717,910 filed Dec. 18, 2012, which issued asU.S. Pat. No. 8,589,757 on Nov. 19, 2013, which is a continuation ofU.S. patent application Ser. No. 13/437,498 filed Apr. 2, 2012, whichissued as U.S. Pat. No. 8,356,229 on Jan. 15, 2013, which is acontinuation of U.S. patent application Ser. No. 13/227,214 filed Sep.7, 2011, which issued as U.S. Pat. No. 8,151,164 on Apr. 3, 2012, whichis a continuation of U.S. patent application Ser. No. 11/928,390 filedOct. 30, 2007, which issued as U.S. Pat. No. 8,028,217 on Sep. 27, 2011,which claims the benefit of U.S. Provisional Application Ser. No.60/863,428 filed Oct. 30, 2006 and U.S. Provisional Application Ser. No.60/863,473 filed Oct. 30, 2006, the contents of which are herebyincorporated by reference herein.

FIELD OF INVENTION

The present invention is related to wireless communication.

BACKGROUND

In third generation partnership project (3GPP) high speed downlinkpacket access (HSPDA), control information that is necessary fordecoding high speed downlink shared channel (HS-DSCH) is transmitted viaa high speed shared control channel (HS-SCCH). Multiple HS-SCCHs may betransmitted to a set of wireless transmit/receive units (WTRUs)associated with a particular cell. The HS-SCCH carries two (2) parts ofdata: part 1 data and part 2 data. The part 1 data includeschannelization code set information, modulation scheme information, etc.The part 2 data includes transport block size information, hybridautomatic repeat request (HARQ) process information, redundancy andconstellation version information, WTRU identity (ID), etc. An HS-SCCHframe includes three time slots. The part 1 data is transmitted in thefirst time slot, and the part 2 data is transmitted in the second andthird time slots.

FIG. 1 shows conventional HS-SCCH encoding. For encoding the part 1data, the channelization code set information X_(ccs) and modulationscheme information X_(ms) are multiplexed to generate a sequence of bitsX₁. Rate ⅓ convolutional coding is applied to the sequence of bits X₁ togenerate a sequence of bits Z₁. The sequence of bits Z₁ is punctured forrate matching to generate a sequence of bits R₁. The rate matched bitsR₁ are masked in a WTRU-specific way using the WTRU ID to produce asequence of bits S₁. Masking in this context means that each bit isconditionally flipped depending on the mask bit value. For the WTRUspecific masking, intermediate code word bits are generated by encodingthe WTRU ID using the rate ½ convolutional coding.

For encoding the part 2 data, the transport block size informationX_(tbs), HARQ process information X_(hap), redundancy versioninformation X_(rv), and new data indicator X_(nd) are multiplexed togenerate a sequence of bits X₂. From the sequence of bits X₁ and X₂,cyclic redundancy check (CRC) bits are calculated. The CRC bits aremasked with the WTRU ID, (X_(ue)), and then appended to the sequence ofbits X₂ to form a sequence of bits Y. Rate ⅓ convolutional coding isapplied to the sequence of bits Y to generate a sequence of bits Z₂. Thesequence of bits Z₂ is punctured for rate matching to generate asequence of bits R₂. The sequences of bits S1 and R2 are combined andmapped to the physical channel for transmission.

The performance of the detection of the part 1 data is influenced by theHamming distance between the masks used for multiple HS-SCCHs. Theconventional method produces a set of masks with a minimum distance ofeight (8). When these minimum distance codes are used, the HS-SCCHdetection performance is not optimal. In addition, with implementationof multiple-input multiple-output (MIMO) for HSDPA, more data need to becarried by the HS-SCCH. Therefore, it is necessary to make more room fortransmission of data related to MIMO implementation in the HS-SCCH.

SUMMARY

A method and apparatus for encoding and decoding HS-SCCH data aredisclosed. For part 1 data encoding, a mask may be generated using aWTRU ID and a generator matrix with a maximum minimum Hamming distance.For part 2 data encoding, CRC bits are generated based on part 1 dataand part 2 data. The number of CRC bits may be less than the WTRU ID.The CRC bits and/or the part 2 data are masked with a mask. The mask maybe a WTRU ID or a punctured WTRU ID of length equal to the CRC bits. Themask may be generated using the WTRU ID and a generator matrix with amaximum minimum Hamming distance. The masking may be performed afterencoding or rate matching.

BRIEF DESCRIPTION OF THE DRAWINGS

A more detailed understanding of the invention may be had from thefollowing description, given by way of example and to be understood inconjunction with the accompanying drawings wherein:

FIG. 1 shows conventional HS-SCCH encoding;

FIG. 2 is a block diagram of an example Node-B for encoding HS-SCCHdata;

FIG. 3 is a block diagram of an example WTRU for decoding HS-SCCH data;and

FIG. 4 shows simulation results for the selection error probability ofthe part 1 data v. signal-to-noise ratio (SNR) comparing the performanceof the two HS-SCCH masking methods (prior art and the present invention)where two HS-SCCH codes are transmitted with different mask distancesdictated the corresponding methods.

DETAILED DESCRIPTION

When referred to hereafter, the terminology “WTRU” includes but is notlimited to a user equipment (UE), a mobile station, a fixed or mobilesubscriber unit, a pager, a cellular telephone, a personal digitalassistant (PDA), a computer, or any other type of user device capable ofoperating in a wireless environment. When referred to hereafter, theterminology “Node-B” includes but is not limited to a base station, asite controller, an access point (AP), or any other type of interfacingdevice capable of operating in a wireless environment.

FIG. 2 is a block diagram of an example Node-B 200 for encoding HS-SCCHdata. The Node-B 200 comprises an encoder 201, a rate matching unit 204,a masking unit 206, a multiplexer 210, a CRC unit 212, a masking unit214, an encoder 218, a rate matching unit 220, and a transceiver 224.The HS-SCCH data comprises part 1 data and part 2 data. The part 1 datais sent to the encoder 202. The encoder 202 performs channel coding onthe part 1 data 201. The channel coded part 1 data 203 is then puncturedby the rate matching unit 204 for rate matching. The rate matched part 1data 205 is then masked with a mask by the masking unit 206. The maskmay be generated based on the WTRU ID 208.

Codes are usually selected for both their performance and for thesimplicity of the decoders. Convolutional codes are a good example ofcodes that have both good performance and low decoder complexity. Thereis of course some tradeoff between performance and decoder complexity.However, the decoder complexity is not a factor when selecting a code touse for the masking because the corresponding decoder need not exist inthe WTRU. All that is needed is the mask itself which can be created bythe much simpler encoder.

The masking unit 206 generates the mask by block coding the WTRU ID 208with a generator matrix which produces masks with a maximumminimum-Hamming-distance. The mask is generated by a vector-matrixproduct of the WTRU ID and the generator matrix. The resulting mask is alinear combination of the rows of the generator matrix. An examplegenerator matrix for (40,16) code is given below. It should be notedthat the generator matrix shown below is provided as an example, not asa limitation, and any other generator matrix may be used alternatively.In this example, the mask is the 40-bit mask, and the WTRU ID is 16-bitslong. This example uses a block code with a specified generator matrixwhich produces masks with minimum distance of twelve (12). This providesmuch better performance when multiple HS-SCCH transmissions at theminimum distance are used.

$\quad\begin{bmatrix}1 & 0 & 0 & 0 & 0 & 0 & 0 & 0 & 0 & 0 & 0 & 0 & 0 & 0 & 0 & 0 & 0 & 0 & 1 & 0 & 1 & 0 & 1 & 0 & 0 & 1 & 0 & 0 & 1 & 1 & 1 & 0 & 0 & 1 & 0 & 0 & 1 & 1 & 1 & 0 \\0 & 1 & 0 & 0 & 0 & 0 & 0 & 0 & 0 & 0 & 0 & 0 & 0 & 0 & 0 & 0 & 1 & 0 & 0 & 1 & 1 & 0 & 0 & 1 & 0 & 1 & 0 & 1 & 0 & 0 & 0 & 1 & 1 & 1 & 0 & 0 & 1 & 0 & 0 & 1 \\0 & 0 & 1 & 0 & 0 & 0 & 0 & 0 & 0 & 0 & 0 & 0 & 0 & 0 & 0 & 0 & 0 & 1 & 0 & 0 & 1 & 1 & 0 & 0 & 1 & 0 & 1 & 0 & 1 & 0 & 0 & 0 & 1 & 1 & 1 & 0 & 0 & 1 & 0 & 1 \\0 & 0 & 0 & 1 & 0 & 0 & 0 & 0 & 0 & 0 & 0 & 0 & 0 & 0 & 0 & 0 & 0 & 0 & 1 & 0 & 0 & 1 & 1 & 0 & 0 & 1 & 0 & 1 & 0 & 1 & 0 & 0 & 0 & 1 & 1 & 1 & 0 & 0 & 1 & 1 \\0 & 0 & 0 & 0 & 1 & 0 & 0 & 0 & 0 & 0 & 0 & 0 & 0 & 0 & 0 & 0 & 1 & 0 & 0 & 1 & 1 & 1 & 1 & 1 & 0 & 1 & 0 & 1 & 1 & 1 & 0 & 0 & 1 & 1 & 0 & 1 & 0 & 1 & 1 & 0 \\0 & 0 & 0 & 0 & 0 & 1 & 0 & 0 & 0 & 0 & 0 & 0 & 0 & 0 & 0 & 0 & 1 & 1 & 0 & 0 & 0 & 0 & 1 & 1 & 1 & 1 & 0 & 1 & 1 & 0 & 0 & 0 & 1 & 0 & 0 & 0 & 0 & 1 & 0 & 1 \\0 & 0 & 0 & 0 & 0 & 0 & 1 & 0 & 0 & 0 & 0 & 0 & 0 & 0 & 0 & 0 & 0 & 1 & 1 & 0 & 0 & 0 & 0 & 1 & 1 & 1 & 1 & 0 & 1 & 1 & 0 & 0 & 0 & 1 & 0 & 0 & 0 & 0 & 1 & 1 \\0 & 0 & 0 & 0 & 0 & 0 & 0 & 1 & 0 & 0 & 0 & 0 & 0 & 0 & 0 & 0 & 1 & 0 & 1 & 1 & 1 & 1 & 0 & 0 & 1 & 0 & 0 & 0 & 0 & 0 & 0 & 0 & 1 & 1 & 0 & 0 & 1 & 1 & 1 & 0 \\0 & 0 & 0 & 0 & 0 & 0 & 0 & 0 & 1 & 0 & 0 & 0 & 0 & 0 & 0 & 0 & 1 & 1 & 0 & 1 & 0 & 0 & 1 & 0 & 0 & 0 & 1 & 1 & 0 & 1 & 1 & 0 & 1 & 0 & 0 & 0 & 1 & 0 & 0 & 1 \\0 & 0 & 0 & 0 & 0 & 0 & 0 & 0 & 0 & 1 & 0 & 0 & 0 & 0 & 0 & 0 & 0 & 1 & 1 & 0 & 1 & 0 & 0 & 1 & 0 & 0 & 0 & 1 & 1 & 0 & 1 & 1 & 0 & 1 & 0 & 0 & 0 & 1 & 0 & 1 \\0 & 0 & 0 & 0 & 0 & 0 & 0 & 0 & 0 & 0 & 1 & 0 & 0 & 0 & 0 & 0 & 0 & 0 & 1 & 1 & 0 & 1 & 0 & 0 & 1 & 0 & 0 & 0 & 1 & 1 & 0 & 1 & 1 & 0 & 1 & 0 & 0 & 0 & 1 & 1 \\0 & 0 & 0 & 0 & 0 & 0 & 0 & 0 & 0 & 0 & 0 & 1 & 0 & 0 & 0 & 0 & 1 & 0 & 0 & 1 & 0 & 1 & 1 & 0 & 0 & 0 & 1 & 1 & 0 & 0 & 0 & 0 & 0 & 0 & 1 & 1 & 1 & 1 & 1 & 0 \\0 & 0 & 0 & 0 & 0 & 0 & 0 & 0 & 0 & 0 & 0 & 0 & 1 & 0 & 0 & 0 & 1 & 1 & 0 & 0 & 0 & 1 & 1 & 1 & 0 & 1 & 1 & 0 & 1 & 1 & 1 & 0 & 1 & 1 & 1 & 1 & 0 & 0 & 0 & 1 \\0 & 0 & 0 & 0 & 0 & 0 & 0 & 0 & 0 & 0 & 0 & 0 & 0 & 1 & 0 & 0 & 0 & 1 & 1 & 0 & 0 & 0 & 1 & 1 & 1 & 0 & 1 & 1 & 0 & 1 & 1 & 1 & 0 & 1 & 1 & 1 & 1 & 0 & 0 & 1 \\0 & 0 & 0 & 0 & 0 & 0 & 0 & 0 & 0 & 0 & 0 & 0 & 0 & 0 & 1 & 0 & 0 & 0 & 1 & 1 & 0 & 0 & 0 & 1 & 1 & 1 & 0 & 1 & 1 & 0 & 1 & 1 & 1 & 0 & 1 & 1 & 1 & 1 & 0 & 1 \\0 & 0 & 0 & 0 & 0 & 0 & 0 & 0 & 0 & 0 & 0 & 0 & 0 & 0 & 0 & 1 & 0 & 0 & 0 & 1 & 1 & 0 & 0 & 0 & 1 & 1 & 1 & 0 & 1 & 1 & 0 & 1 & 1 & {.1} & 0 & 1 & 1 & 1 & 1 & 1\end{bmatrix}$

Conventionally, the mask is generated by encoding the WTRU ID 208 usingthe rate ½ convolutional coding. The minimum Hamming distance of theconventional masks is eight (8). The improved Hamming distance of themasks generated by the present invention results in a performanceimprovement of the part 1 HS-SCCH decoder at the WTRU. FIG. 4 showssimulation results for the selection error probability of the part 1data v. SNR comparing the performance of the two HS-SCCH masking methods(prior art and the present invention) where two HS-SCCH codes aretransmitted with different mask distances dictated the correspondingmethods. FIG. 4 shows performance improvement when using the mask withthe Hamming distance of twelve (12) compared to the mask with theHamming distance of eight (8).

Referring again to FIG. 2, the part 1 data 201 and the part 2 data 211are sent to the CRC unit 212 to calculate CRC bits. The CRC bits areattached to the part 2 data 211. The number of CRC bits may be less thanthe length of the WTRU ID so that more data, (e.g., data for MIMO), maybe included as the part 2 data. The combined part 2 data and the CRCbits 213 are sent to the masking unit 214. The masking unit 214 performsmasking to the CRC bits or CRC bits plus some or all of the part 2 datawith a mask, which will be explained in detail below. The masked part 2data and CRC bits 217 are encoded by the encoder 218. The encoded part 2data and CRC bits 219 are punctured by the rate matching unit 220. Therate matched part 2 data and CRC bits 221 and the rate matched part 1data 209 are multiplexed by the multiplexer 210 and sent to thetransceiver 224 for transmission.

In accordance with one embodiment, the masking unit 214 may generate amask having a size equal to or smaller than the size of the CRC bitsplus the part 2 data. A portion of the mask is extracted and applied tothe CRC bits and the remaining portion of the mask is applied to all orpart of the part 2 data. The mask may be generated using the WTRU ID 216and a generator matrix as disclosed above with respect to part 1 datamasking to maximize the minimum Hamming distance of the masks.

In accordance with another embodiment, the WTRU ID may be used as amask. The length of the WTRU ID may be longer than the CRC bits.Therefore, a part of the WTRU ID is used to mask the CRC bits and theremaining of the WTRU ID is used to mask the part 2 data. In accordancewith yet another embodiment, the WTRU ID is punctured to be the samelength as the CRC bits and the punctured WTRU ID is used to mask the CRCbits.

In accordance with still another embodiment, the masking unit 214 may bemoved between the encoder and the rate matching unit. The masking unit214 generates a mask of length equal to the rate matched part 2 data andCRC bits 221. The masking unit 214 then applies the mask to the encodedpart 2 data and CRC bits 219. Alternatively, the masking unit 214 may bemoved between the rate matching unit 220 and the multiplexer 210, andapplies the mask to the rate matched part 2 data and CRC bits 221. Themask may be 80-bits long. The mask may be generated using the WTRU ID216 and a generator matrix as disclosed above with respect to part 1data masking to maximize the minimum Hamming distance of the masks.

FIG. 3 is a block diagram of an example WTRU 300 for decoding HS-SCCHdata. The WTRU 300 includes a transceiver 302, a de-multiplexer 304, ade-masking unit 306, a de-rate matching unit 310, a decoder 312, ade-rate matching unit 314, a decoder 316, a de-masking unit 318, and aCRC unit 322. The transceiver 302 receives a HS-SCCH transmission 301including a first part on a first time slot of an HS-SCCH framecorresponding to the part 1 data and a second part on the second andthird time slots of the HS-SCCH frame corresponding to the part 2 data.The first part 305 a and the second part 305 b are de-multiplexed by thede-multiplexer 304.

The first part 305 a is de-masked by the de-masking unit 306. Thede-masking unit 306 generates the same mask used at the Node-B in thesame way using the WTRU ID 308. The mask may be generated with the WTRUID 308 and the generator matrix as disclosed above. The de-rate matchingunit 310 reverts the puncturing performed at the Node-B on the de-maskedfirst part 309. The de-rate matched first part 311 is then decoded bythe decoder 312 to output part 1 data 313. The part 1 data is also sentto the CRC unit 322.

The second part 305 b is de-rate matched by the de-rate matching unit314 to revert the puncturing performed at the Node-B. The de-ratematched second part 315 is then decoded by the decoder 316 to outputpart 2 data (may or may not be masked at the NodeB) and masked CRC bits317. The masked CRC bits and optionally the masked part 2 data 317 arede-masked by the de-masking unit 318. The de-masking unit 318 uses thesame mask used at the Node-B for the de-masking. The mask may be theWTRU ID 320, punctured WTRU ID, or a mask generated by using the WTRU ID320 and a generator matrix. The de-masking unit 318 outputs de-maskedpart 2 data and CRC bits 321 to the CRC unit 322. The CRC unit 322 thenperforms a CRC check with the part 1 data 313, the part 2 data, and CRCbits.

The de-masking unit 318 may be moved between the decoder 316 and thede-rate matching unit 314, or between the de-rate matching unit 314 andthe de-multiplexer 304 depending on the masking scheme performed at theNode-B. In this case, the mask may be 80-bits long, and the mask may begenerated using the WTRU ID 216 and a generator matrix as stated aboveto maximize the minimum Hamming distance of the masks.

Although the features and elements of the present invention aredescribed in particular combinations, each feature or element can beused alone without the other features and elements or in variouscombinations with or without other features and elements. The methods orflow charts provided may be implemented in a computer program, software,or firmware tangibly embodied in a computer-readable storage medium forexecution by a general purpose computer or a processor. Examples ofcomputer-readable storage mediums include a read only memory (ROM), arandom access memory (RAM), a register, cache memory, semiconductormemory devices, magnetic media such as internal hard disks and removabledisks, magneto-optical media, and optical media such as CD-ROM disks,and digital versatile disks (DVDs).

Suitable processors include, by way of example, a general purposeprocessor, a special purpose processor, a conventional processor, adigital signal processor (DSP), a plurality of microprocessors, one ormore microprocessors in association with a DSP core, a controller, amicrocontroller, Application Specific Integrated Circuits (ASICs), FieldProgrammable Gate Arrays (FPGAs) circuits, any other type of integratedcircuit (IC), and/or a state machine.

A processor in association with software may be used to implement aradio frequency transceiver for use in a WTRU, user equipment (UE),terminal, base station, radio network controller (RNC), or any hostcomputer. The WTRU may be used in conjunction with modules, implementedin hardware and/or software, such as a camera, a video camera module, avideophone, a speakerphone, a vibration device, a speaker, a microphone,a television transceiver, a hands free headset, a keyboard, a Bluetooth®module, a frequency modulated (FM) radio unit, a liquid crystal display(LCD) display unit, an organic light-emitting diode (OLED) display unit,a digital music player, a media player, a video game player module, anInternet browser, and/or any wireless local area network (WLAN) module.

What is claimed is:
 1. A Node-B comprising: a processor configured tocalculate cyclic redundancy check (CRC) bits for a data block; theprocessor configured to mask the CRC bits with wireless transmit/receiveunit (WTRU) identity (ID) bits; the processor configured to attach themasked CRC bits to the data block; and a transmitter configured totransmit the data block.
 2. The Node-B of claim 1 wherein the data blockis used to calculate the CRC bits.
 3. The Node-B of claim 1 wherein thetransmitter is configured to transmit the data block over a physicalchannel.
 4. The Node-B of claim 1 wherein the transmitter is configuredto transmit the data block over a shared channel.
 5. A methodimplemented in a Node-B comprising: calculating cyclic redundancy check(CRC) bits for a data block; masking the CRC bits with wirelesstransmit/receive unit (WTRU) identity (ID) bits; attaching the maskedCRC bits to the data block; and transmitting the data block.
 6. Themethod of claim 5 wherein the data block is used to calculate the CRCbits.
 7. The method of claim 5 wherein the data block is transmittedover a physical channel.
 8. The method of claim 5 wherein the data blockis transmitted over a shared channel.
 9. A wireless transmit/receiveunit (WTRU) comprising: a receiver configured to receive a data block,wherein the data block includes masked cyclic redundancy check (CRC)bits; a processor configured to de-mask the CRC bits in the receiveddata block, wherein identity (ID) bits of the WTRU are used to de-maskthe CRC bits; and the processor further configured to perform a CRCcheck on the received data block using the de-masked CRC bits.
 10. TheWTRU of claim 9 wherein the CRC bits have been calculated using the datablock.
 11. The WTRU of claim 9 wherein the receiver is configured toreceive the data block over a physical channel.
 12. The WTRU of claim 9wherein the receiver is configured to receive the data block over ashared channel.
 13. A method implemented in a wireless transmit/receiveunit (WTRU), comprising: receiving a data block, wherein the data blockincludes masked cyclic redundancy check (CRC) bits; de-masking the CRCbits in the received data block, wherein identity (ID) bits of the WTRUare used to de-mask the CRC bits; and performing a CRC check on thereceived data block using the de-masked CRC bits.
 14. The method ofclaim 13 wherein the CRC bits have been calculated using the data block.15. The method of claim 13 wherein the data block is received over aphysical channel.
 16. The method of claim 13 wherein the data block isreceived over a shared channel.